Method and apparatus for treating sewage



June 14, 1949. s. l. ZACK 2,473,323

' IETHOD AND mums FOR mum-ma smu Filed Kay 29, 1945 aspen-shut 1 I mvcumn I Jamel J; 24 WMW ATTORNEY June 14 1949. s. 1. ZACK METHOD AND APPARAWS FOR TREATING SEWAGE Filed May 29. 1945 2 Sheets-Sheet 2 mvsmo Jawuel 1241/6 proved impossible of PatentedJlme 14, 1949 HE'I'HOD'AND APPARATUS non rename SEWAGE Samuel I. Zack, Paxtan Pa;

Application May 29, 1945, Serial No.

16 Claims. (Cl. 210-6) 7 attainment. 7 Moreover, the area occupiedby an activated sludge plant lit the amount of sewage In addition to the foregoing, it is known that about 60% of the purifying has been accom- Thus a large is recirculated to obtain the last one-third of the purification. This prolonged treatment has been necessitated by the fact that relatively short and units, thus The structure well adapted to for be factory built reducing costs.

As a result of the ability to vary steps individually to flt varying conditions of operation. it is possible to materially reduce the size'oi' equipment needed and thus save both space and ex- Dense.

In addition, no sludge pumps are needed, a single drive may operate all sludge return blades, a speedy and economical return of sludge is eii'ected, and reaeration issimple, eifective and economical to prevent septicity in sludge.

Each successive step serves to agglomerate and separate sludge from liquid from which much has already been removed, thus a successively on smaller increments of impurities. The aeration in each step may be varied to meet the altered state of the sewage treated.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

Fig. 1 is aplan view of a typical small plant of the present invention;

Fig. 2 is a fragmentary perspective of the parts shown in Fig. 1;

Fig. 3 is a sectional end view of the structure of Fig. 1, along the line 3-3 of Fig. 1;

Fig. 4 is a plan view of an alternative larger equipment form; V

Fig. 5 is a sectional 5-5 of Fig. 4; and r Fig. 6 is a diagrammatic sectional view, analogous to Fig. 5, showing an ment of settling chamber analogous to Fig. 5 but for still larger equipment.

end view along theline mately rectangular and adapted to hold the sewone hour usually about of the impurities will settle in a similar settling chamber or, with 20,0 P. P. M. at the intake, a purer liquid will run out through eflluent troughs II and I4, which are further described below. Here it may be enough to say that the liquid running of! through the troughs l3 and M will then often carry 80 P. P. M. impurities.

To eflect this purifying, the sewage is shown as aerated, by air blown through an air main I! which runs lengthwise of the chamber near a side wall l8 and is shown provided with a nummain l5.

. first purpose bein ber of projecting spaced porous diffuser tubes so that air bubbles enter into the sewage a little distance from the wall It with the result that the rising bubbles of air cause. as viewed in Fig. 3, a slow clockwise current in the sewage. It is possible to introduce the airlby mere agitation, but that is usually less emcient except in small installations.

This clockwise current flows down along the opposite wall it of the aeration chamber, passing a side opening I9 at the bottom of the wall l8 and then returning along the bottom 20 to pass the The opening It serves a double purpose, the to allow liquid in chamber II to pass quietly into the bottom of a settling chamber 2|, formed by the common wall l8 and then slowly upward to the surface where the liquid overflows into the spaced eiiluent troughs I3 and II which run longitudinally along the chamber 2| and lie with their tops serving as weirs, just at the liquid surface, to receive and carry oil the liquid. To minimize disturbing the liquid in the chamber 2|, the eilluent troughs are spaced apart about a third or half of the width of the chamber 2| and receive liquid from both sides.

The second purpose of the opening I! is to admit settled sludge for recirculation before the sludge starts to septify. I

To eflect this recirculation of sludge, the chamber 2| is shown with a sweeping blade 22 adapted to oscillate across an arcuate portion 23 of the bottom of chamber 2|, so that as the'blade 22 approaches the opening I19, heaped up sludge in front of it sweeps along a short upcurve 24 of the are 23 and pushes some or all of the sludge through the opening I! where it encounters the down current 01' the chamber l along the wall It, and may tumble down a short slope 25 to the bottom 20. Thus part of the settled sludge is continuously returned at intervals to the chamber Ill.

The part to be returned may be adjusted by altering the travel of the blade 22, and it may also be altered by varying the length of the opening 26 which leads to a sludge concentrating pocket 21 and its valved run-oi pipe 28. The opening 26 may be a substantial fraction of the length of the chamber 2|. The sweeping blade 22 serves to keep sludge from accumulating, sweeps sludge into the removable opening, and, therefore, keeps sludge from becoming septic.-

To vary the opening 26 there is diagrammatically shown an adjustable sliding gate 29 adapted to close or partly close the opening 25 at will.

The blade 22 is shown as mounted on arms 35 near its ends and fast to an oscillating shaft 3| driven in any desired manner'as by an electric variable speed motor drive so that the blade 22 usually sweeps over the discharge opening 26, not far from the middle of its travelonce a minute or possiblyonce in ten minutes, depending on conditions.

Thus the settling chamber 2| is continually discharging part of the sludge at the opening 20 and returning the rest of the sludge to the aeration chamber II to modify the actions taking of the chamber |l through the chamber 2| and theme by overflowing into the eiiluent troughs l3 and I4 along their long sides which serve as control weirs.

The ellluent runs from the troughs l3 and I4 into a cross-trough 32 shown at the end of the settling chamber 2| which confines the eiiluent until it reaches a continuation trough 33 which extends the width of a second aeration chamber 24 and which is adapted to let the eilluent overflow quietly from its low side 35 along the surface of the liquid in the second aeration chamber 34, which may be built as if partitioned off from chamber III or aligned with it.

The second aeration chamber 34 may tical with the chamber ll, including a continuation 36 of the air main II, with projecting spaced porous diffuser tubes 31 like the tubes I1, and circulating its contained liquid by rising air bubbles coming from the tubes 31 so the liquid flows across the chamber 34 and down the opposite wall 38, and past a bottom opening in the wall 34.

- The opening may be identical with the opening l9, admitting sludge from an adjacent settling chamber 39, the sludge is pushed in by an oscillating blade 40 carried by arms 4| on a continuation 42 of the shaft 3|. The chamber 39 may be built as if partitioned oi! the chamber 2| or aligned with it.

The chamber 34, like the chamber ll, delivers its eilluent through its bottom opening to the settling chamber 39 whence it overflows into long l3 and I4.

The liquid may remain in the chambers 34 and 39 about the same time as in the chambers II and 2|, and deposit another 60% of its contained impurities, delivering the sludge in small lots through an opening like the opening 26, and independently adjustable by an adjustable gate to gary the amount of removed sludge in a given ime.

The troughs 43 'and 44 deliver the liquid efiluent into a cross trough 45 which conflnes the efliuent until it reaches a continuation 45 at a third aeration chamber 41, which is adapted to let the eflluent overflow quietly from its low side 48 along the surface of the liquid in the third aeration chamber 41.

The third aeration chamber 41 may be identical with the chamber Ill, including a continuation 49 of the air main IS, with projecting spaced porous Adifiusion tubes 54, like the tubes l1 and circulating the contained liquid by rising air bub bles coming from the tubes 50, so the liquid flows across the chamber 41 and down the opposite wall 5|, and past a bottom opening in the wall 5|.

- That opening may be identical with the opening it, admitting sludge from an adjacent settling chamber 52, which is pushed in by an oscillating blade 53 carried by arms 54 on a continuation I of the shaft 3|.

The chamber 41, like the chamber I0, delivers its efliuent through its bottom opening into the settling'chamber 52 whence it overflows into long sgriac; llezliuent troughs 55 and 51 like the troughs I an be idenare diagrammatically shown oppositely projecting run 011' ll, since apparently 60% of the contained impurities are deposited in settling chamber ll, leaving only a negligible content which can be settled out in any reasonable time.

The settling chambers 39 and 52 may include valved sludge openings or pockets :6 identical with the pocket 26 of chamber 2|, and deliver to a sludge pipe 59.

For treating larger amounts of sewage, it may be advisable to operate in larger units such as in Figs. 4 and 5.

In Fig. 4 is shown a form of central aeration chamber it receiving sewage which isfed .by a suitable trough, not shown, and especially adapted to hold large amounts of sewage, and which may be fifteen to forty feet wide and fifteen feet deep.

In Fig. 4 the aeration is shown as eifected by diifuser pipes 6| projecting horizontally from cated a little above a low central ridge 63 in the chamber floor. an upward current in the sewage which tends to flow away from the center of the surface and down along the side walls 64, 65.

In the form shown, the sewage flows out through a bottom opening 66 near the bottom of each wall 64, 65, into each side settling chamber 81 in which settles sludge.

- Each chamber 61 is shown as having an arcuate outer bottom and side 68 across which sweeps a sludge blade 69 carried by arms 10 fixed to an oscillating shaft 1| joumalled at the center of the are 68.

The blades 69 sweep into and out of the openso that rising bubbles of air create an air supply pipe 62 lolugs 66 to sweep back into the aeration chamber It a proper amount of sludge to effect the desired reactions, sweeping up over short up curves 12 below the openings 66, and also sweeping over suitable openings 13 into sludge pockets 14 so that valves (not shown) may control the amount of sludge drawn oiT.

If the settling chambers become too large for a suitable are 68, for arms 10, it may be advantageous to modify the arms 10 by hinging them (Fig. 6) at 15 so they may sweep over an efiective arc 16 with its sludge pocket 14, and then the blades may be carried by the bent arms along a flat stretch H of the bottom, and later, with the arms straightened, over a rising arc is to the opening 66.

valved extensions ill to the chambers and to interiorly disposed extensions I5, 36 and 49.

As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and Having thus described certain embodiments of the invention in some detail, what is claimed is:

1. In a sewage treatment apparatus, the combination with an aeration chamber to receive sewage and means for introducing sewage thereinto, of an adjacent settling chamber receiving sewage therefrom through a bottom opening between the chambers, a device adapted to be operated from the exterior of settling chamber for returning part of the settled sludge from the settling chamber to the aeration chamber through said bottom opening between the chambers, a separately settable device through which excess sludge is removed, an eiiluent connection from the settling chamber including troughs serving as weirs substantially throughout the length of the chamber and drawing liquid through the bottom opening, and an elongate aerating device in the aeration chamber adjacent a bottom wall thereof adapted to maintain circulation of sewage in the aeration chamber by supplying air thereto.

2. In a sewage treatment apparatus, the combination with an aeration chamber to receive sewage and means for introducing sewage into said chamber, of an adjacent settling chamber receiving sewage therefrom through a bottom opening between the chambers, a device adapted to be operated by means disposed outside the settling tank for returning part of the settled sludge from the settling chamber to the aeration chamber through said bottom opening between the chambers, a separately settable device through which excess sludge is removed, an eiiiuent connection from the settling chamber including troughs serving as weirs substantially throughout the length of the chamber and drawing liquid through the opening, and an aerating device in the aeration chamber adjacent and extending along the wall away from the opening lower part of said aeration to maintain circulation of sewage in the aeration chamber by supplying air thereto.

3. In a sewage treatment apparatus, the combination with an aeration chamber to receive sewage and means for introducing sewage thereadjacent settling chamber receiving the aerated sewage through a between the chambers, a device operable by drive means for returning part of the settled sludge from the settling chamber to the aeration chamberthrough the bottom opening between the chambers, a separately settable device through which excess response to exteriorly disposed drive means removing'sludge from the floor of the settling chamber and returning part of-it through said opening to the aeration chamber and also sweepinfl Part of the sludge away from the flowing sewage through a floor opening in the settling chamber, and an eflluent weir adjacent an upper part of the settling chamber.

5. In a sewage treatment apparatus. the com- I binatlon with an aeration chamber to receive sewage and sewage introducing means, of an adjacent settling chamber having one wall in common with the aeration chamber and including an opening near the bottom of the wall forming the eilluent means for the aeration chamber, an aeration device carrying air into the sewage adjacent the opposite wall and lower part of the aeration chamber and including an air supply pipe and porous air delivery element, a swinging blade movable substantially against said common wall adjacent said bottom opening for removing sludge from the floor of the settling chamber and returning part of it through said opening to the aeration chamber and also sweeping part of the sludge away from the flowing sewage through a floor opening in the settling chamber,

a drive shaft connected with and movable to actuate said blade, and an ei'iluent weir at an upper part of the settling chamber.

6. The combination with an aeration chamber adapted to receive sewage and means for introducing sewage thereinto, of a settling chamber separated from said aeration chamber by a wall having a bottom opening, an eflluent weir spaced above the bottom of the settling chamber drawing sewage through the opening, a swinging blade in the settling chamber returning settled sludge to the aeration chamber through the opening and also removing sludge away from the flowing sewage through a bottom opening, an air introducing device in the aeration chamber along a wall facing the wall opening, a second aeration chamber substantially aligned with the first aeration chamber, a second settling chamber substantially aligned with the first settling chamber, a trough adapted to feed eiiluent from said first settling chamber to the second aeration chamber, a wall separating the second aeration chamber from the second settling chamber and having an effluent opening for the second aeration chamber, an air introducing device in the second aeration chamber along a wall facing the wall opening, a second swinging blade in the second settling chamber returning settled sludge to the second aeration chamber through the opening and also removing sludge away from the flowing sewage through a bottom opening, means adapted to actuate said swinging blades, and an eilluent device for the second settling chamber.

7. The combination with a series of-aeration chambers having walls and means for introducing sewage to an aerationchamber, of a series of aeration devices adapted to circulate sewage in the chamber, a series of settling chambers beyond one set of walls and communicating with the aeration chambers by bottom openings in the walls, curved bottoms for the settling chambers having discharge openings for sludge, blades adapted for sweeping across said bottoms and partially into said wall openings to remove sludge partly through said wall openings for returning sludge to aeration and partly through said bottom openings for removing sludge from the body of flowing sewage, movable means connected with said blades for actuation, thereof, and means for gonducting efliuent away from the settling chamers.

4 8. The combination ing sewage, of a series of aeration devices adapted to circulate sewage in the chamber, a series of settling chambers beyond one set of walls and connected with the aeration chambers by bottom openings in the walls, curved bottoms for the settling chambers having discharge openings for sludge for removing sludge from the body of flowing sewage, devices for varying the size of the discharge openings, blades adapted for sweeping movement across said bottoms and partially through said bottom openings in the walls to remove sludge partly through said wall openings for returning sludge to aeration and partly through said bottom openings in a ratio determined by the size of the openings, and a movable means connected with said blades for actuation thereof. a

9. The process of treating sewage which includes introducing sewage into and circulating it and aerating it in an aeration chamber, withdrawing the sewage from its bottom, settling sludge out of the sewage in a separate adjacent settling chamber, returning part of the sludge to the aeration chamber, separating out at the bottom and removing from the body of flowing seawage the rest of the settled sludge, overflowing the eiiiuent at the top into a second aeration chamber, withdrawing the sewage from its bottom, settling further sludge out of the sewage in a separate adjacent settling chamber, returning part of the sludge to the second aeration chamber, separating out at the bottom and removing from the body of flowing sewage the rest of the settled sludge, and overflowing the eifluent at the top.

10. The process which includes aerating incoming sewage, flowing aerated sewage through an opening and settling part of the sludge out of the aerated sewage, returning part of the settled sludge to the incoming sewage and momentarily blocking the major portion of said opening, discharging from the body of flowing sewage the rest of the settled sludge by gravity at the bottom, separately reaerating the remainder of the sewage, settling a separately controlled further amount of sludge from said remainder, returning part of the residual settled sludge to the reaerated remainder, discharging from the body of flowing sewage the rest of the settled sludge by gravity at the bottom, and overflowing the effluent from it.

11. The process which includes aerating incoming sewage in a tank so as to keep it circulattank, removing said sewage remainder from said second aeration tank by withdrawal from the lower part thereof and settling a separately controlled part of the sludge from it in a second settling tank, returning a portion of the settled part to said remainder in said second aeration tank, at the lower part thereof for reaerating it, discharging by gravity at the bottom of the second settling tank the rest of said settled part of the sludge, overflowing the remainder of the sewage from the second settling tank and reaerating it with a series of aeration chambers having walls and means for introduccarried by said rod a third time in a third aeration tank, removing sewage from said third aeration tank by withdrawal from the lower part thereof, settling sludge in a third settling tank, returning to said third reaerating tank at the lower part thereof a separately controlled part of the last settled sludge, discharging by gravity at the bottom of the third settling tank the rest of the last settled sludge, and separately discharging the remaining sewage.

12. The process of purifying sewage which includes aerating it, mechanically removing part of the sludge, mechanically returning part of the removed sludge, discharging from the body of flowing sewage by gravity the remainder of the removed sludge, reaerating the sewage from which said part has been removed, mechanically removing more sludge, mechanically returning av separately controlled part of said latter mentioned removed sludge to the sewage being reaerated, discharging by gravity from the body of flowing sewage the remainder of the removed sludge, and carrying off the sewage fromwhich the sludge has been removed,

13. The process of purifying sewage which includes aerating it, flowing aerated sewage through an opening and settling sludge from said aerated sewage to include the major part which can be settled before contained oxygen is exhausted, separating part of the settled sludge and returning it to the oncoming sewage for further aeration and momentarily reversing the direction of sewage flow through said opening during said sludge separating, separately removing the remainder of the settled sludge from the body of flowing sewage, separately reaerating the remainder of the sewage, settling further sludge, returning part of the settled further sludge for said reaeration, separately discharging the remainder of the sludge from the body of flowing sewage, and separately discharging the rest of thesewage.

14. The combination with an aeration chamber having a side wall and sewage introducing means, of a settling chamber having a bottom of which a major part is flat and extends to a location adjacent an opening through said side wall, said bottom also including an exit opening for discharging sewage from the body of flowing sewage, an aerating device in the aeration chamber, an efliuent weir in the settling chamber drawing sewage from the aeration chamber through the wall, an oscillatable shaft, an

settled sludge to the the side wall opening part through the exit 15. The combination with a series of aeration chambers having side walls and sewage introducing means associated with one of said chambers, of a separate settling chamber for each aeration chamber and connected therewith by a aeration chamber through and delivering a separate opening.

chamber adjacent one edge of tling chamber adapted to deliver part of the settlings to a separate discharge bottom opening having a lesser length than that of its settling chamber and adapted to return part of the settlings through the connecting opening to the aeration chamber, means adapted to conduct effluent away from each settling chamber, a pair of arms carrying each scraper, a movable shaft supporting said arms and a single drive connected with said shaft for actuation thereof.

16. In a sewage treatment device, an aeration chamber, means for introducing sewage into said chamber, a settling chamber provided with a partly arcuate bottom and having a relatively wide opening communicating with the aeration the bottom and having a sludge exit opening in the arcuate bottom extending across a relatively narrow portion of the width of said settling chamber, a sludge scraper movable over the bottom to deliver part of the sludge through the sludge exit opening and movable substantially against an edge portion of said relatively wide opening adapted to push sludge through the latter opening into the aeration chamber, and a trough adapted to carry off from the settling chamber efliuent from which sludge has settled.

SAMUEL I. ZACK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,123,011 Ripley Dec. 29, 1914 1,139,024 Frank May 11, 1915 1,717,780 Imhofl June 18, 1929 1,738,362 Downes Dec. 3, 1929 1,820,977 Imhofl. Sept. 1, 1931 1,982,246 Fischer Nov. 27, 1934 1,985,854 Downes Dec, 25, 1934 1,994,887 Downes et a1 Mar. 19, 1935 2,024,345 Eirod Dec. 17, 1935 2,027,370 Currie -4 Jan. 14, 1936 2,048,640 Sperry July 21, 1936 2,089,160 Darby Aug. 3, 1937 2,090,384 Durdin'3d Aug. 17, 1937 2,160,838 Don June 6, 1939 2,168,208 Jenks Aug. 1, 1939 2,225,437 Nordell Dec. 17, 1940 2,258,398 Ward Oct. 7, 1941 2,381,579 Durdin 3d Aug. 7, 1945 2,394,413 Walker Feb. 5, 1946 FOREIGN PATENTS Number Country Date 27,240 Great Britain 1905 466,743 Germany Oct-12, 1928 OTHER REFERENCES 

